Spindle control mechanism



INVENTORS. WILLIAM F. GROENE HAROLD J. SIEKMANN w. F. GROENE ETAL SPINDLE CONTROL MECHANISM July 18, 1944.

Filed Oct. 27, 1941 nuaaai Patented July 18, 1944 SPINDLE CONTROL MECHANISM William F. Groene and Harold J. Siekmann, Cincinnati, Ohio, assignors to The R. K. Le Blond Machine Tool Company, Cincinnati, Ohio, a

corporation of Delaware Application October 27, 1941, Serial No. 416,682

9 Claims.

This invention pertains to spindle control mechanism for machine tools and more particularly to the stopping of rotating work spindles at the completion of a cutting cycle and to provide means for inching or Jogging the work spindles when setting the cutting tools. This application involves certain improvements in mechanism shown in our Patent #2,192,437 issued March 5, 1940, and our co-pending application Serial #386,688, filed April 3, 1941.

The chief object of this present invention is to provide apparatus, particularly in conjunction with the arrangement shown in the above application Serial Number 386,688, whereby the work spindle and associated driving motor are allowed to rotate a plurality of revolutions during the initial hydraulic braking thereof so as to decelerate them without violent shocks to the apparatus which usually occurs when these members are decelerated in less than a revolution of the work spindle.

It is also an object to provide in conjunction with the limit switch, in the apparatus of the above application, for plugging off the hydraulic braking motor to stop work spindle rotation, a centrifugal switch arranged in series with this limit switch and which centrifugal switch is controlled by the rotation of the work spindle in such a way that the work spindle must be rotating at a predetermined slow speed, regardless of the number of revolutions required to decelerate the work spindle to this predetermined speed by the hydraulic braking motor, before this control limit switch for effecting final stopping of spindle can be rendered operative.

Further objects and advantages of this invention will appear from the detailed description of the drawing:

Figure I is a circuit diagram of the electrichydraulic operating and control mechanism shown diagrammatically applied to a double center drive lathe.

Figure II is a diagrammatic representation of the electric driving motor, the hydraulic braking motor, and associated transmission mechanism of a typical double center drive lathe to which this invention may be effectively applied.

For purposes of an exemplary disclosure, this invention is shown applied to a double center drive lathe of a character for example as shown in Patent #2,069,107, dated January 26, 1937, a spindle driving arrangement for such a lathe being shown diagrammatically in Figure II comprising the work spindle I, consisting of a pair of center drive ring gears 2 and 3, which are driven through suitable idler gears 4, by the pinions 5, fixed on the drive shaft 6. The drive shaft 6 is driven by the main drive electric motor I which has a pulley 8 mounted on its motor shaft 9, connected by suitable belts Ill to the driving pulley ll mounted on the pulley shaft l2 upon which shaft is fixed the driving pinion l3 which drives the gear I! fixed on the drive shaft 6, whereby the motor may rotate the center drive gears 2 and 3. Also connected to the shaft 9 of the motor I is the hydraulic braking motor l5, which may be of the usual gear pump or piston pump type.

The supply of fluid pressure for the hydraulic control system may be derived from the usual hydraulic fluid pressure pump I 6 driven by an electric motor H, which draws fluid through the suction line l8 from the fluid reservoir I9 and delivers fluid under pressure through the pressure line 20. Drainage from a relief valve in the pump it for maintaining pressure in the line 20 is exhausted through the line 2| into the drain line 22, which returns fluid to the reservoir l9.

In the operation of the lathe, when the main drive motor 1 is operating driving the work spindle I during the cutting operation, the hydraulic braking motor I5 is also being driven by the motor shaft 9. Under these conditions, fluid is discharged from the exhaust port 23 of the hydraulic braking motor l5, through the line 24, freely through the deceleration control valve 25. The control valve is a three-position valve having a spring centered" normal position a, a "break or jog position b efiected by operation of its solenoid 28, and a plug" position 0 effected by operation of its solenoid 29. The effect of these positions of the control valve 21 on the various lines connected to the valve is indicated in Figure I of the drawing and may be tabulated as follows:

(a) Spring centered:

Line 26 connected to line 30. Lines 38 and 40 cut off at valve.

(c) Solenoid 29 energized:

Line 26 connected to line all-(blocked at check valve 31). Line 30 connected to line 40.

When the main drive motor is operating as,

above, the control valve 21 is in the spring centered position with both solenoids 28 and 23 deenergized, whereby fluid from the line 28 passes freely through the valve 21 into the line 30, and returns by way of the lines 3|, 32 and 33 to the intake port 34 of the fluid pressure motor 15, thus completing a circuit of tree fluid circulation. The relief valve is so designed that fluid from the line 32 cannot pass through it to the line 24 or 28 from the discharge line 35 01' this valve 21. Also, fluid cannot escape from this circuit through the line 38, the check valve 31 (which is arranged for tree flow from line 38 to 38) and the line 38, since the control valve 21 when in spring centered position closes off the line 38. Pressure supply is maintained in this circuit of free circulation from the line 28 connected to the fluid pressure pump l8.

At the completion of the cutting cycle, electric power is cut oil from the main drive motor 1 by conventional electrical control apparatus (not shown), which renders the limit switch LS--I effective, so that the first time it is actuated by the dog 33, carried by the ring gear 2 alter electric power is cut oil from the main drive motor 1, the solenoid 28 of the control valve 21 will :be energized thus moving the valve to the brake position. When in this position, the line 28 is connected to the line 40, which in turn is connected to the flow restricting or slow speed control valve 4|, discharge from this valve 4| passing into the drain line 22. Line is connected to line 38 which in turn is connected to the check valve 31 and the line 38 connected to the line 3|. Thus there is no flow of fluid from the pressure lines 30-3l into the lines'38 and 38 as they are in a closed circuit. Fluid pressure does'however, continue to be'applied to the line 32 from the line 20. As soon as the solenoid 28 is operated, fluid is exhausted from the Port 23 of the hydraulic motor l5 passes into the slow speed control valve 4|, which is capable of allowing only a small amount of fluid to be discharged from the motor to be passed into the drain line 22, resulting in high pressure being built up in the line 24, thus restricting rotation of the hydraulic motor I 5. The larger part of this fluid discharge under pressure is passed into the line through the deceleration control valve 25, which discharge recirculates through the motor l5 while the machine is decelerating to a predetermined slow speed,'at which time the pressure in the line 24 drops to the pressure in line 35 and the valve 25 thereby closes with no further discharge into the line 35. Adjustment of the valve 25 thus regulates the rate of deceleration of the machine which in this arrangement is usually set to permit several revolutions of the spindle to take place during the deceleration thereof.

This deceleration process continues until the hydraulic motor has slowed down to the point where the discharge from the port 23 can be completely carried through the slow speed control valve 4|, whereupon the motor l5 will continue to operate slowly at this rate of discharge through the valve 4| as it now is driven by the fluid pressure from the hydraulic pump l8, through the lines 28, 3|, 32, and 33 connected to the inlet port 34.

As the spindle is brought to the slow speed of rotation, a centrifugal control switch 42 driven by suitable means such as the belt 43 from the motor 1 becomes operative to render the limit switch LS-Z operative to actuate the solenoid 29 of the valve 21. At this time when t e g 4m sition. By the use of the centrifugal switch 42 in this way the rate of deceleration of the work spindle in no way effects the operation of the limit switch LS2, so that this limit switch does not become efiective until the spindle has reached a predetermined speed in a single revolution or in a plurality of revolutions. Thus any desired rate of deceleration may be obtained while still eflfecting the flnal positive stopping of the spindle from a predetermined slow speed.

When in this position, the line 28 is connected to the line 38 which is blocked off by the check valve 31 so that no fluid can pass out of the line 38. Thus with the hydraulic motor operating at the predetermined slow speed, its exhaust port is blocked or plugged ofl bringing the hydraulic motor 15 to a stop, since there is insufllcient energy in the machine when thus rotating slowly to efiect any discharge through the valve 25 into the line 35. Line 30 is. connected to the line 43 which allows the fluid pressure from the line 20 to flow through the slow speed control valve 4| into the drain line 22 at a sufliciently slow rate to maintain the pressure in the line 28. It is to be noted that when thus stopped, fluid pressure from the lines 30-3! is equally applied to each side of the hydraulic motor 15. This pressure is applied to the intake port 34 of the motor l5, through the lines 32 and 33 and to the exhaust port through the line 38, the check valve 31, line 38, control valve 21, line 28, deceleration valve 25, and the line 24. In this way, creeping oi the hydraulic motor I5 is avoided, which might otherwise occur if the pressure was allowed to remain only on the intake side of the hydraulic pump I5, since under these conditions the plugged ofi exhaust circuit would allow the motor l5 to be slowly rotated by fluid pressure enterim the port 34.

When it is desired to jog the center drive gears 2 and 3 it is only necessary to provide suitable electrical means for cutting out the limit switches LS-I and LS-2 and to alternately energize one or the other of the solenoids 28 and 29 of the control valve 21. When the solenoid 28 is energized the center drive gears rotate at a predetermined slow speed and when solenoid 29 is energized the center drive gears are substantially instantly stopped as described above.

Having thus fully set forth and described our invention, what we claim as new and desire to secure by United States Letters Patent is:

1. In a machine tool, a work spindle driving motor, a hydraulic braking motor connected to and'driven by said spindle driving motor, a work spindle driven from said motor, a fluid pressure pump, means for connecting pressure from said pump at all times to the input side of said hydraulic braking motor, a discharge connection from said hydraulic braking motor to a control valve, a decelerating relief valve interconnected in the line between said output of said hydraulic braking motor and said control valve and means whereby the pressure discharge from said decelcrating relief valve is connected to the input side of said hydraulic braking motor, a flow restricting valve connected to said control valve and discharging into a fluid reservoir associated with said fluid pressure pump, means in said control valve for normally positioning said valve in a position whereby discharge from the output of said hydraulic braking motor is normally transmitted to the input side of said braking motor freely through said decelerating relief valve, while fluid pressure is maintained in a circuit of free circulation from said fluid pressure pump. means associated with said. .work spindle eiiected by its rotation for operating said control valve immediately after power is disconnected from said spindle driving motor for connecting discharge from said exhaust side of said hydraulic braking motor to the input side of said flow restricting valve thereby causing fluid initially to be partially transmitted to said flow restricting valve while the major portion of said discharge from said hydraulic braking motor passes under pressure through said decelerating relief valve into the input side of said hydraulic braking motor, said flow restricting valve functioning to continue slow rotation of said hydraulic driving motor at a predetermined speed under the influence of pressure from said fluid pressure pump, and a centrifugal limit switch operable by a predetermined-rate of rotation of said work spindle for rendering a second switch, operated by the position of rotation of said work spindle, eflective for moving said control valve to a position, when discharge from said exhaust side of said hydraulic braking motor is of an amount capable of being carried by said flow restricting valve, whereby said control valve is efl'ective to positively shut off discharge of fluid from the output of said hydraulic braking motor by connecting said discharge to the output side of a check valve and in connecting fluid pressure from said hydraulic pump to the input side of said flow restricting valve while at the same time maintaining this pressure, on the input side of said hydraulic braking motor, said check check valve being interconnected between said control valve and said pressure line from said hydraulic pump to the input side of said hydraulic braking motor whereby fluid pressure from said hydraulic pump may be automatically applied simultaneously to both said input and output sides of said hydraulic braking motor when brought to rest by operation of said control valve to its last mentioned position.

2. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a hydraulic braking motor connected to rotate with said spindle and driving motor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnecting said ports to permit fluid discharge from said exhaust port to enter said inlet. port when said hydraulic brakin motor is being driven by rotation of said spindle and driving motor; means for applying said source of fluid pressure to said ports during the flow of fluid from the exhaust port to said intake port; a control valve in said interconnecting means for said ports;

means rendered effective by the operation of said valve to prevent flow of fluid between said ports to arrest rotation of said hydraulic braking motor; means in said valve for connecting said source of fluid pressure to a flow restrict-' ing valve when said control valve is operated to arrest the flow of fluid between said ports; means returning discharge from said flow restricting valve to said source of fluid pressure; and control means operable by the rate of rotation of said spindle and driving motor eifective to operate said control valve for arresting rotation of said hydraulic braking motor at a predetermined rate of rotation of said spindle and driving motor; and means operable at a predetermined rotative position of said work spindle to render said control means eflective.

3. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle;

a hydraulic braking motor connected to rotate with said spindle and driving motor; a source prevent flow of fluid between said ports to arrest rotation of said hydraulic braking motor; means in said valve for connecting said source of fluid pressure to a flow restricting valve when said control valve is operated to arrest the flow of fluid between said ports; means returning discharge from said flow restricting valve to said source of fluid pressure; a decelerationcontrol valve interconnected between said hydraulic braking motor and said control valve having means connecting the discharge from said deceleration control valve to the inlet port of said hydraulic braking motor, said deceleration control valvebeing eflective, when said control valve is operated to prevent flow of fluid between said ports of said hydraulic braking motor, to momentarily permit discharge of fluid under pressure to escape from saidexhaust port to said inlet port of said hydraulic brakin motor to cause the deceleration in the speed of rotation of said hydraulic braking motorin a predetermined interval of time; and control means operable by the rate of rotation of said work spindle and driving motor effective at a predetermined speed of rotation of said work spindle to operate said control valve to cause it to prevent flow oi fluid between said ports of said hydraulic braking motor to arrest rotation of said work spindle and driving motor; and means operable at a predetermined rotative position of said work spindle to render said control means eflective.

4. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a hydraulic braking motor connected to rotate with said spindle and driving motor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnectingsaid ports to permit fluid discharge from said exhaust port to enter said inlet port when said hydraulic motor is being driven by rotation of said spindle and driving motor; and means for applying said source of fluid pressure to said ports during the flow of fluid from said exhaust port to said intake port; a control valve in said interconnecting means for said ports; means rendered effective by the operation of said valve to permit restric ed flow of fluid between said and control means operable by the rate of rotation of said work spindle and driving motor effective to render said valve operative to cut of! flow between said intake and exhaust ports of said fluid pressure braking motor at a predetermined rate of rotation of said work spindle and driving motor; and means operable at a predetermined rotative position of said work spindle to render said control means effective.

5. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a hydraulic braking motor connected to rotate with said spindle and driving motor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnecting said ports to permit fluid discharge from said exhaust port to enter said inlet port when said hydraulic braking motor is being driven by rotation of said spindle and driving motor; means for applying said source of fluid pressure to said ports during the flow of fluid from the exhaust port to said intake port; a control valve in said interconnecting meansfor said ports; a check valve associated with said control valve; means for actuating said control valve to connect discharge from said exhaust port of said hydraulic braking motor in non-flow direction to said check valve to arrest rotation of said braking motor; and control means operable by the rate of rotation of said work spindle driving motor for rendering said control valve operative to shut off flow between said inlet and exhaust ports of said hydraulic braking motor; and means operable at a predetermined rotative position of said work spindle to render said control means eiIective.

6. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a hydraulic braking motor connected to rotate with said spindle and driving motor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnecting said ports to permit fluid discharge from said exhaust port to enter said inlet port when said hydraulic motor is being driven by rotation of said spindle and driving motor; means for applying said source of fluid pressure to said ports duringthe flow of fluid from the exhaust port to said intake port; a control valve in said interconnectin means for said ports; a check valve having its exhaust side connected to said control valve; means for actuating said control valve to connect discharge from said exhaust port of said hydraulic braking motor to the nonflow exhaust side of said check valve to arrest rotation of said braking motor; means whereby said check valve automatically permits application of said source of fluid pressure to both of said ports of said hydraulic braking motor when said control valve is operated to stop rotation of said hydraulic braking motor; and control means operable by the rate of rotation of said work spindle and driving motor for rendering said control valve operative at a predetermined speed of rotation of said work spindle and driving motor to shut ofi flow of fluid between said ports of said hydraulic braking motor; and means op erable at a predetermined rotative position of said work spindle to render said control means eiiective.

'7. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a, hydraulic braking motor connected to rotate with said spindle and driving motor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnecting said ports to permit fluid discharged from said exhaust port to enter said inlet port when said hydraulic braking motor is being driven by rotation 01' said spindle and driving motor; means for applying said source of fluid pressure to said ports during the flow of fluid from the exhaust port to said intake port; a control valve in said interconnecting means for said ports; means rendered eilective by the operation of said valve to prevent flow oi fluid between said ports to arrest rotation oi. said hydraulic braking motor; means in said valve for connecting said source of fluid pressure to a flow restricting valve when said control valve is operated to arrest said flow of fluid between said ports and means returning discharge from said flow restricting valve to said source of fluid pressure; means actuated by the rotation of said spindle and driving motor to render said control valve operative; control means, operable by the rate of rotation of said work spindle and driving motor, efiective at a predetermined speed of rotation thereof to permit operation of said control valve for shutting off flowof fluid between the ports of said hydraulic braking motor; and means operable at a predetermined rotative position of said work spindle to render said control means effective.

8. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a hydraulic braking motor connected to rotate with said spindle and drivingmotor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnecting said ports to permit fluid discharged from said exhaust port to enter said inlet port when said hydraulic motor is being driven by rotation of said spindle and driving motor; means for applying said source of fluid pressure to said ports during the flow of fluid from the exhaust port to said intake port; a control valve'in said interconnecting means for said ports; means effective by the operation of said valve to permit restricted flow of fluid between said ports to reduce the rate of rotation of said hydraulic braking motor to a predetermined slow speed; means in said-valve for connecting said discharge from the exhaust port of said hydraulic braking motor to a flow restricting valve and for disconnecting said source of fluid pressure from said exhaust port of said hydraulic braking motor when said control valve is operated to restrict said flow of fluid between said ports; means returning discharge from said flow restricting valve to said source of fluid pressure; means actuated by the rotation of said spindle and driving motor to render said control valve operative; control means, operable by the rate of rotation of said work spindle and driving motor, to render said control valve operative to cut on flow between said intake and exhaust ports of said fluid pressure braking motor when said work spindle and driving motor are rotating at a predetermined rate of speed; and means operable at a predetermined rotative position of said work spindle to render said control means eflfective.

9. In a machine tool; a work spindle; a spindle driving motor for rotating said work spindle; a hydraulic braking motor connected to rotate with said spindle and driving motor; a source of fluid pressure; inlet and exhaust ports for said hydraulic braking motor; means interconnecting said ports to permit fluid discharged from said exhaust port to enter said inlet port when said hvdraulic motor is being driven by rotation of said spindle and driving motor; means for applying said source of fluid pressure to said ports during the flow of fluid from the exhaust port to said intake port; a control valve in said interconnecting means for said ports; means in said valve for connectingsaid-discharge from the exhaust port of said hydraulic braking motor to a flow restricting valve and for disconnecting said source of fluid pressure from said exhaust port 01 said hydraulic braking motor when said control valve is operated to restrict said flow of fluid between said ports; and means returning discharge from said flow restricting valve to said source of fluid pressure; and a deceleration control valve interconnected between ,7

said hydraulic braking motor and said control valve; and means connecting the discharge from said deceleration control valve to the inlet port of said hydraulic braking motor to permit lim-v ited flow of fluid between said ports; control means, operable by the rate of rotation of said work spindle and driving motor, to render said control valve operative to cut oil flow between said intake and exhaust ports of said fluid pressure braking motor when said work spindle and driving motor are rotating at a predetermined rate 01' speed: and means operable at a predetermined rotative position of said work spindle to render said control means eflective.

WILLIAM F. GROENE. HAROLD J. SIEKMANN. 

